The present invention relates to resin structures of good vapor and/or liquid transmission resistance, and their use. In particular, the invention relates to resin moldings of specific transmission resistance and workability, which are obtained by forming a specific morphology of polyolefin resin and polyphenylene sulfide resin (hereinafter referred to as PPS resin) and are favorable for vapor and/or liquid barrier articles, to such resin structures favorable for containers and pipes for storage and transportation of liquid chemicals such as oil and gasoline, to those favorable for wrapping and packaging materials and containers for foods and medicines, and to their use.
Polyolefin resins such as polyethylene and polypropylene are the most popular plastics that are widely used for daily necessaries, toys, machine parts, electric and electronic parts, and automobile parts. The recent requirement increasing in the art is for gas-barrier (transmission-resistant) resin articles capable of preventing the contents from leaking out and protecting them from the open air for ensuring the safety and the storage stability of the contents and for protecting the environment from pollution. However, since polyolefin resins are poorly resistant to liquid chemical and vapor transmission through them, their use is often limited, and it is desired to improve them.
For improving for the physical properties of such polyolefin resins, resin compositions and moldings consisting of polyolefin resin and polyamide resin of good transmission resistance have heretofore been proposed in the art. The method could improve the transmission resistance of the resin compositions and moldings over that of moldings of polyolefin resin alone, but is still unsatisfactory. Therefore desired is a technique of further improving the transmission resistance of polyolefin resin structures.
For fuel tanks and oil tanks for automobiles, converting metallic containers into plastic containers is now actively investigated, as plastics are lightweight and easy to mold and work, their design latitude is broad, and they are easy to handle. The matter of importance with such plastic containers is that they do not leak the contents and can protect the contents from the open air for ensuring the safety and the storage stability of the contents and for protecting the environment from pollution. Polyethylene, polypropylene and other polyolefin containers are the most popular plastic containers, but their barrier properties against gasoline and other specific oils are unsatisfactory. Therefore, it is difficult to directly use them for fuel tanks and oil tanks for automobiles. For such use, in general, they are worked into multi-layer structures by coating them with a barrier layer of resin of high transmission resistance.
One typical example of the resin to form such a barrier layer is polyamide resin (for example, as in JP-A 220738/1983). However, the recent tendency in the field of automobile fuel is being toward using a mixture of gasoline and alcohol, gasohol, for which the plastic containers obtainable in the above-mentioned prior art are unsatisfactory in point of their barrier properties. Therefore desired is a technique of further improving the barrier properties of plastic containers.
On the other hand, it is known that PPS resin has extremely good barrier properties against liquid chemicals such as gasoline and automobile oil, and against water and carbon dioxide. Blow-molded containers and tubular structures of such PPS resin (for example, as in JP-A 90216/1987, 255832/1986, 32816/1991), and multi-layer structures with a barrier layer formed of a specific PPS resin and a modified polyolefin (for example, as in JP-A 190980/1994) have been proposed. However, since its interlayer adhesiveness to other resin is poor, PPS resin has some problems in that its coextrusion and lamination with other resin materials such as polyethylene, polypropylene and other polyolefins is difficult and its main component must be an expensive specific PPS resin. For these reasons, the application range of PPS resin is limited.
The present invention is to improve the transmission resistance of polyolefin resin, and its object is to provide resin structures of specifically improved liquid chemical and vapor transmission resistance, not detracting from the properties such as toughness, moldability and workability intrinsic to polyolefin resin, especially to provide polyolefin-PPS resin structures favorable for vapor and/or liquid barrier articles, and to provide multi-layer structures of good transmission resistance, moldability, workability, interlayer adhesiveness and toughness that are favorable to plastic containers and can be stably and economically formed into good plastic containers.
We, the present inventors have studied to solve the problems noted above, and, as a result, have found that, when a polyolefin resin and a PPS resin are mixed in a specific ratio optionally along with an inorganic filler in such a controlled manner that the PPS resin phase in morphology in the resulting resin composition could form a dispersed configuration capable of being a continuous phase or a laminar (layered) phase in the shaped structure of the resin composition, then the above-mentioned problems can be solved. On the basis of this finding, we have reached the present invention.
Specifically, the invention provides the following:
(1) A thermoplastic resin structure formed of a resin composition that comprises substantially (a) from 5 to 80% by volume of a polyolefin resin and (b) from 20 to 95% by volume of a polyphenylene sulfide resin, which is characterized in that, in morphology therein seen through electronic microscopy, the polyphenylene sulfide resin (b) forms a matrix phase (continuous phase) and the polyolefin resin (a) forms a disperse phase;
(2) The thermoplastic resin structure of above (1), for which the blend ratio of the polyolefin resin (a) and the polyphenylene sulfide resin (b) is such that the former accounts for from 55 to 80% by volume and the latter for from 20 to 45% by volume;
(3) The thermoplastic resin structure of above (1), for which the blend ratio of the polyolefin resin (a) and the polyphenylene sulfide resin (b) is such that the former accounts for from 60 to 75% by volume and the latter for from 25 to 40% by volume;
(4) A thermoplastic resin structure formed of a resin composition that comprises (a) from 15 to 85% by volume of a polyolefin resin and (b) from 15 to 85% by volume of a polyphenylene sulfide resin, which is characterized in that, in morphology therein seen through electronic microscopy, both the phase of the polyphenylene sulfide resin (b) and the phase of the polyolefin resin (a) are substantially continuous phases;
(5) A thermoplastic resin structure formed of a resin composition that comprises (a) from 55 to 95% by volume of a polyolefin resin and (b) from 5 to 45% by volume of a polyphenylene sulfide resin, which is characterized in that, in morphology therein seen through electronic microscopy, the polyolefin resin (a) forms a continuous phase and the polyphenylene sulfide resin (b) forms a laminar disperse phase;
(6) The thermoplastic resin structure of any of (1) to (5), for which the polyolefin resin (a) is at least one selected from polyethylene, polypropylene, ethylene/xcex1-olefin copolymers, [copolymers of (ethylene and/or propylene) and (unsaturated carboxylic acid and/or unsaturated carboxylate)], and [copolymers of (ethylene and/or propylene) and (unsaturated carboxylic acid and/or unsaturated carboxylate) in which at least a part of the carboxyl groups are modified into metal salts];
(7) The thermoplastic resin structure of any of (1) to (6), which contains (c) from 0.5 to 200 parts by weight, relative to 100 parts by weight of the total of the polyolefin resin (a) and the polyphenylene sulfide resin (b), of an inorganic filler;
(8) Containers for transportation or storage of liquid chemicals or gases, which are obtained by working the thermoplastic resin structure of any of (1) to (7);
(9) Attached parts for containers for transportation or storage of liquid chemicals or gases, which are obtained by working the thermoplastic resin structure of any of (1) to (7);
(10) Moldings of the thermoplastic resin structure of any of (1) to (7), which are formed in at least one method of injection molding, injection compression molding or compression molding;
(11) A multi-layer structure with a barrier layer, in which the barrier layer is formed of the thermoplastic resin structure of any of (1) to (7);
(12) The multi-layer structure of (11), wherein a neighboring layer is formed on one or both surfaces of the barrier layer, and the neighboring layer is a thermoplastic resin layer differing from the thermoplastic resin structure that forms the barrier layer;
(13) The multi-layer structure of (12), wherein the thermoplastic resin to form the neighboring layer is at least one selected from polyolefin resins, thermoplastic polyester resins, polyamide resins, polycarbonate resins and ABS resins;
(14) The multi-layer structure of (12), wherein the thermoplastic resin to form the neighboring layer is at least one selected from polyolefin resins, thermoplastic polyester resins and polyamide resins;
(15) The multi-layer structure of (12), wherein the thermoplastic resin to form the neighboring layer is an ethylene homopolymer and/or an ethylene/xcex1-olefin copolymer having a melt flow rate of from 0.01 to 30 g/10 min and a density of from 0.90 to 0.97 g/cm3;
(16) The multi-layer structure of (12), which has an adhesive layer formed between the barrier layer and the neighboring layer;
(17) The multi-layer structure of (16), wherein the adhesive layer is formed of a modified polyolefin having a degree of crystallinity of at most 50% and containing from 0.01 to 10% by weight of an unsaturated carboxylic acid or its derivative grafted thereon;
(18) The multi-layer structure of (17), wherein the adhesive layer comprises from 60 to 99 parts by weight of a modified polyolefin having a degree of crystallinity of at most 50% and containing from 0.01 to 10% by weight of an unsaturated carboxylic acid or its derivative grafted thereon, and from 1 to 40 parts by weight of a tackifier;
(19) The multi-layer structure of any of (11) to (18), which is formed through coextrusion;
(20) The multi-layer structure of any of (11) to (19), which is formed into multi-layered tubes or multi-layered blow moldings through coextrusion.